The present invention relates to a piston mechanism and, more specifically, to an airlift piston mechanism for a piston compressor.
A conventional piston mechanism is generally comprised of a cylindrical casing defining a piston chamber, a piston mounted in the piston chamber, and a link coupling the piston to an external motor for enabling the piston to be reciprocated in the piston chamber upon operation of the external motor. In order to reduce friction between the cylindrical casing and the piston and prevent air leakage, the piston is made having two annular grooves around the periphery, and two O-rings are respectively mounted in the annular grooves and disposed in contact with the inside wall of the cylindrical casing. This arrangement still cannot greatly reduce friction between the piston and the cylindrical casing. Friction between the piston and the cylindrical casing affects the performance of the piston mechanism.
The primary object of the present invention is to provide an airlift piston mechanism, which greatly reduces friction between the cylindrical casing and the piston during reciprocating motion of the piston in the cylindrical casing.
It is another object of the present invention to provide airlift piston mechanism, which greatly improves the output efficiency of the piston.
To achieve these objects, the airlift piston mechanism is comprised of a cylindrical casing, a piston, at least one seal ring, and a link. The cylindrical casing comprises a piston chamber, an air inlet adapted for guiding outside air into the piston chamber, an air outlet adapted for guiding air from the piston chamber to the outside, and a check valve installed in the air inlet for enabling outside air to pass to the piston chamber and prohibiting inside air from escaping out of the piston chamber to the outside. The piston is axially slidably mounted in the piston chamber for reciprocating motion, comprising an air accumulation chamber, an air hole in communication between the air accumulation chamber and the piston chamber, a check valve mounted in the air hole to let air pass from the piston chamber to the air accumulation chamber and to prohibit air from escaping out of the air accumulation chamber to the piston chamber, at least one annular groove extended around the periphery thereof, and an air passage in communication between the at least one annular groove and the air accumulation chamber. The at least one seal ring is respectively mounted in the at least one annular groove of the piston, each having at least one radial through hole. The link is coupled to the piston and adapted for reciprocating the piston in the piston chamber. During reciprocating motion of the piston in the piston chamber, the seal rings are floating subject to the air pressure in the air accumulation chamber, reduction friction between the cylindrical casing and the piston.